On Mon, Sep 11, 2023 at 10:33:08AM +0800, linan666@xxxxxxxxxxxxxxx wrote:
> From: Li Nan <linan122@xxxxxxxxxx>
>
> If a socket is processing ioctl 'NBD_SET_SOCK', config->socks might be
> krealloc in nbd_add_socket(), and a garbage request is received now, a UAF
> may occurs.
>
> T1
> nbd_ioctl
> __nbd_ioctl
> nbd_add_socket
> blk_mq_freeze_queue
> T2
> recv_work
> nbd_read_reply
> sock_xmit
> krealloc config->socks
> def config->socks
>
> Pass nbd_sock to nbd_read_reply(). And introduce a new function
> sock_xmit_recv(), which differs from sock_xmit only in the way it get
> socket.
>
I am wondering why not grab queue usage counter before calling nbd_read_reply()
for avoiding such issue, something like the following change:
diff --git a/drivers/block/nbd.c b/drivers/block/nbd.c
index df1cd0f718b8..09215b605b12 100644
--- a/drivers/block/nbd.c
+++ b/drivers/block/nbd.c
@@ -837,9 +837,6 @@ static void recv_work(struct work_struct *work)
while (1) {
struct nbd_reply reply;
- if (nbd_read_reply(nbd, args->index, &reply))
- break;
-
/*
* Grab .q_usage_counter so request pool won't go away, then no
* request use-after-free is possible during nbd_handle_reply().
@@ -852,6 +849,9 @@ static void recv_work(struct work_struct *work)
break;
}
+ if (nbd_read_reply(nbd, args->index, &reply))
+ break;
+
cmd = nbd_handle_reply(nbd, args->index, &reply);
if (IS_ERR(cmd)) {
percpu_ref_put(&q->q_usage_counter);
Thanks,
Ming
